In conventional integrated circuits, memory cells often have manufacturing defects that reduce the yield of semiconductor devices. Further, memory cells can become less effective during the lifetime of a semiconductor device. In some conventional solutions, a fuse element is used to provide redundant or more effective memory cells to replace defective or ineffective memory cells.
In conventional techniques, fuse elements are designed with non-volatile memory, rather than volatile memory. A volatile memory is a memory that loses its contents when power is removed from the memory. A non-volatile memory is a memory that retains its contents when power is removed from (i.e., not applied to) the memory. Conventionally, memory (i.e., material used for data storage) is formed and fabricated using various types of material, such as semiconductors, silicon dioxide, conductive or complex metal oxides (CMO), and others.
Some memory elements can be designed to store data as resistive values. However, conventional solutions are often affected by problems such as disturb effects. For example, a read disturb occurs when the resistive value of a memory element is corrupted by multiple accesses to the memory element. The resistive value of a memory element changes (i.e., increases or decreases) in small increments for each read access to the memory element, resulting in a corrupted resistive value over multiple read accesses to the memory element. Since non-volatile memory elements are read at a higher frequency than volatile memory elements, a fuse element designed with non-volatile memory such as CMO is more susceptible to read disturbs.
FIG. 1 illustrates a conventional fuse element. Here, conventional fuse element 100 includes latch 110, gates 120-122, memory elements 130-132, and enable signal 140. Latch 110 typically functions as a temporary data storage system, storing data in response to an active signal on enable signal 140. Memory elements 130-132 are designed to store data as resistive values. For example, memory element 130 has a resistive value indicative of a programmed state and memory element 132 can have a resistive value indicative of an erased state. Gates 120-122 control the flow of data communicated between latch 110 and memory elements 130-132. In conventional fuse elements (e.g., fuse element 100), gates 120-122 are typically implemented as transistors. However, resistive values of memory elements 130-132 may be corrupted by disturb effects.
There are continuing efforts to improve fuse element technology for use with non-volatile memory.
Although the previous drawings depict various examples of the invention, the invention is not limited by the depicted examples. It is to be understood that, in the drawings, like reference numerals designate like structural elements. Also, it is understood that the depictions in the FIGS. are not necessarily to scale.